National Register of Historic Places: April 1981; National Historic Landmark: August 1985

History of Building/Site

Original Brief:

The need for a dam through the Colorado River was recognized by the federal government as early as 1902 when President Theodore Roosevelt established the Bureau of Reclamations, which sent out a team of engineers to investigate and report on the harnessing, control, and possible uses of the Colorado River. The river had periodically flooded, endangering the farming communities of the surrounding valleys. In 1922, Reclamation Bureau engineer Arthur P. Davis issued a report the construction of a dam for year-round irrigation of the surrounding land. In this report, Davis also suggested the construction of a hydroelectric power plant that could recover construction costs by selling the electricity generated to the rapidly expanding cities of Southern California. Six years later, the Swing-Johnson Bill authorized federal funding for the construction of the dam. In 1929, Congress passed the Boulder Canyon Project Act and the project was set in motion. Due to the sheer size and scale of the project, a conglomerate construction and engineering firm, Six Companies, was selected for the construction of the dam and power plant for $48,890,995. Shortly thereafter, architect Gordon B. Kaufman was retained by the Bureau of Reclamation to revise and improve the original facades put forth by Reclamation engineers. Kaufman modified the original scheme, which according to him was “an orderly series of small vertical shadows punctuated by the larger shadows of the elevator and utility towers” (Wilson 302-3), by replacing the traditional ornament– classical cornices, columns, eagles, and the like– with clean lines and volumes that unify the complex and give the dam its distinctly modern aesthetic. His design is particularly evident in the smooth interlocking forms of the dam crest, with sculptured turrets rising seamlessly from the cement face. The intake towers and spillways were also reworked: Kaufmann added lights to the top of the intake towers for a night effect and the powerhouse was redone in a modernist, reductive-classical style. The federal government officially dedicated the dam on September 30, 1935. Construction was completed in 1936.

Architectural and other Designer(s): Architects: Gordon B. Kaufman, Los Angeles-based architect enlisted to aesthetically improve the original designs put forth by Board of Reclamation engineers and Frank Crowe, U.S. Construction Engineer, Bureau of Reclamation, aided in the design of the hydraulic systems for the dam and oversaw much of the engineering during construction; Artists: Allen True, worked alongside Kaufman to design the interiors of the power plant and responsible for the Navajo-inspired terrazzo floor mosaics in the lobby of the power plant; Oskar J.W. Hansen, designed the bronze statues and bas-reliefs, located respectively on the dam crest and elevator towers.

Others associated with Building/Site: Arthur P. Davs: Director and Chief Engineer for the Bureau of Reclamation, chief author of the Fall-Davis Report, the first to suggest the construction of a dam and hydroelectric plant at Boulder Canyon; Walker Young: General Superintendent for Six Companies, Inc.

Significant Alteration(s) with Date(s): Generators were updated and new generators were added to the power plant from 1936 until 1961 as part of the original plan. As a major source of electrical power for the defense industry, the Hoover Dam was considered a primary military target during World War II. In 1942, a series of 24’-0” long steel and concrete “pillbox” bunkers with six gun ports were added to the dam in response to the attack on Pearl Harbor. Of the several bunkers constructed at this time, only one survives today. An octagonal visitor’s center, whose form takes its cue from the dam’s lakeside intake towers, as well as a parking garage were added to the Nevada side of the complex in 1996. The new center and parking facility were designed by Spencer Associates and not received favorably by architectural critics. In 2001, construction began on a new composite steel and concrete arch bridge for the Hoover Dam Bypass Project. This bridge will divert vehicular traffic from U.S. 93 1,500 feet to the south in order to relieve traffic congestion from the dam itself and to increase highway capacity and safety. The bypass is slated for completion in mid-2010. When it is completed it will be the longest bridge of its kind in the western hemisphere, spanning the 1,900 feet valley.

Current Use: The Bureau of Reclamations continues to operate the dam and hydroelectric power plant that supplies water to southern California, principally Los Angeles, as well as the southern California Edison Company, which also subcontracts power to Arizona and Nevada.

Current Condition: The Bureau of Reclamation has limited vehicular traffic to two lanes until the bypass is finished.

General Description:

The Hoover Dam is among the largest and earliest of the Bureau of Reclamation’s massive multi-purpose dams. By providing flood control, irrigation water, and electric power, the dam made possible increased population and agricultural production in large areas of the Southwest. At the time of its construction, it was the largest reinforced concrete structure and hydroelectric plant in the world. The dam created Lake Mead, which at 115 miles, was the largest artificial body of water in the world at the time of completion. The reservoir has become a popular year-round recreation area for boating, fishing, and swimming. The dam itself is a smooth crescent-shaped structure, rising 730’ from the canyon bedrock and measuring a quarter of a mile across the top, with two intake towers and four spillways along the crest and a power plant that is embedded within. It serves as a bridge across the Black Canyon, with U.S. 93 and a pedestrian walkway on either side. Kaufman streamlined the design into one visually unified structure. He treated the various components and extrusions as continuations of the dam face. The four large towers are treated very simply, allowing the form and the material itself to be emphasized. The two outer towers were originally used for utilities and public restrooms, from which the public could descend 530’-long elevators to access the internal galleries, the floors of which are inlaid with True’s Navajo-and-centrifugal-inspired mosaics. The inner towers served as public entrances to the dam and contain the only ornament along the dam: Hansen’s 30’ low-relief bronze statues, the “Winged Figures of the Republic” that sit on 6’ diorite pedestals and flank a 142’ flag pole. Art historian Wilson notes: “these surrealistic apparitions underscored the unreality of a dam and lake in the middle of a hostile desert.” The inner intake towers are set with clock faces set for Pacific Standard Time. The dam quickly became an icon of modernism both stylistically and for its unprecedented use of new materials and new construction techniques. The alliance between the engineering and architecture of the dam makes it an entirely modernist structure, a union of function and form.

Construction Period:

Concrete arch-gravity storage dam.

Original Physical Context:

The Hoover Dam is located in the Black Canyon of the Colorado River, along the Nevada and Arizona border.

Evaluation

Technical Evaluation:

At the time of construction, no dam of this scale had ever been attempted and many previously untried techniques were required for its construction and engineering. Over five million barrels of cement; one-hundred sixty-five cars of sand, gravel, and cobble; thirty-five tons of structural reinforcing steel; nine-hundred cars of hydraulic machinery; and over one-thousand miles of steel pipe were used to build the structure. Every state in the union was required to supply materials. The most challenging aspect of the project was the pouring and cooling of concrete. To prevent stresses and cracks, the dam was built in a series of interlocking trapezoidal concrete pours. Each form of concrete contained cooling coils of 1” thin-walled steel pipe. Refrigerated water was circulated through the coils for further cooling. Once the layer was cooled, the refrigerated coils were cut off and pressure grouted by pneumatic guns. The dam has been rated by the American Society of Civil Engineers as one of the Seven Modern Civil Engineering Structures in the United States.

Social:

The Hoover Dam was completed as part of the United States Department of the Interior’s Bureau of Reclamation. Construction began at the start of the Great Depression. Several thousand workers were hired to excavate and build this massive concrete structure. Workers were divided into three shifts so that concrete was continuously poured 24 hours a day, seven days a week until the completion of the project. Working conditions were dangerous and the pay was low, yet many accepted the work as so few jobs were available at the time. Ninety-six deaths occurred during construction. A bronze sculpture and plaque along the dam crest commemorates them. The sheer size and scale of the Hoover Dam animated the national imagination and offered an alternative narrative to the Great Depression as it expressed the power of technology, embodied a sense of hope for the future, and highlighted humanity’s ability to control and alter the course of nature.

Cultural & Aesthetic:The austerity, imposing size, and stripped-down forms of the dam express the sheer scale of the project as well as the cutting-edge technology required for its construction. The dam, with its massively thick streamlined concrete forms, falls stylistically within Kaufman’s later works, distinctive for their emphasis on massively thick concrete walls. This is seen in the Los Angeles Times Building and Hollywood Palladium.

Historical:

The Hoover Dam was lauded in the press as an engineering marvel. Kaufman’s reworked facades were received favorably by the architectural community. Upon completion, it was the largest concrete structure in the world as well as a significant addition to the Modernist Movement as one of the first public work structures of its scale designed in a modern aesthetic.

General Assessment:A significant inclusion in the Modern Movement, the Hoover Dam continues to operate as a dam and power house, which generates power to a substantial part of the southwest.

Stevens, Joseph E. Hoover Dam: An American Adventure. Norman, OK: University of Oklahoma
Press, 1990.
United States Department of the Interior, Bureau of Reclamation. Hoover Dam. Washington: U.S.
Government Printing Office, 1950.
Wilson, Richard Guy. “American Modernism in the West: Hoover Dam.” In Thomas Carter, ed.
Images of an American Land. Alberqueque: University of New Mexico Press, 1997.